There is a clear trend to compose systems, e.g. mobile phones, in a modular fashion wherein various modules are coupled together via a universal interface. The modules may exchange data with each other via a connection, such as a bus or a network. The available bandwidth of the connection has to be distributed between various requesters. The assignment of the connection may be made for each point in time independently or being clustered in time slots, such as in a TDMA system. Most important classes of data traffic are guaranteed throughput (GT) and best effort (BE) traffic. GT traffic implies that a prescheduled amount of data is exchanged at well-defined time instances. Isochronous data traffic is a particular case thereof, where data is transmitted at regular time-intervals. BE traffic class does not guarantee this but provides the best possible data rate. In the sequel data of the first class will also be denoted as guaranteed throughput data or GT data. The second class of data will also be denoted as best effort data or BE data. In particular for mobile devices, such as mobile phones, it is important to reduce power consumption. An important way to achieve this is to power down a data connection when there is no traffic. This feature is known in PCI Express. If it is detected that a data link is idle, it is powered down in about 20 bus cycles (8 ns). Subsequently it should stay in the power down mode during 50 bus cycles (20 ns). However, if there are frequent requests for data transmission, the idle time is too short to enable a power down.